This description relates to acoustic transducer array signal processing.
Acoustic transducers (sometimes called drivers) of loudspeaker systems may be grouped in arrays (for example, acoustic dipoles or pairs of acoustic monopoles) to increase the power of, or to directionally control the magnitude and phase of, the radiation from the transducers. Arrays may take the form of acoustic dipoles or pairs of acoustic monopoles, for example.
As shown in FIG. 7, an acoustic dipole 702 (for example, an open-backed speaker that radiates sound equally from the front and rear faces of its diaphragm) effectively radiates energy in two lobes 704a and 706a centered along an axis 707 at θ=±90 on graph 700, with the waves from the front and back canceling out along the mid-plane 708 of the dipole 702 at θ=0. The region of cancellation, referred to as a null, can be used to create psychoacoustic effects, such as altering the direction from which a sound is perceived to originate. As shown in FIGS. 7B and 7C, the lobes may be asymmetric (704b, 706b in FIG. 7B; 704c, 706c in FIG. 7C), and there may be nulls on only one plane (e.g., along null axis 710 in FIG. 7B) or on more than one plane (e.g., along null axes 712, 714 in FIG. 7C). FIG. 7B also illustrates that there may be variation between an ideal radiation pattern 716 and an actual radiation pattern 718 generated by real transducers (not shown).